The present invention is directed to substrates for wallcovering, and more specifically to a gauze substrate formed of a synthetic continuous, multi-filament polymeric yarn.
Products such as vinyl wallcovering conventionally must be provided with a gauze substrate mechanically affixed to the rear surface thereof. The gauze substrate is compatible with a wet bonding agent (water based glue) to hold the glue in place adjacent the rear of the sheet material until the sheet has been applied to a selected surface (a wall in the case of wallpaper). When the glue or resin has had an opportunity to cure, the gauze substrate (and thus the wallcovering) is bonded to the surface. Vinyl sheet materials will not, in and of themselves, either absorb or hold the glue in place during the curing process, because vinyl is a hydrophobic material.
The gauze substrate is generally woven from a spun yarn formed principally of cellulosic fibers such as cotton. As used herein the term "principally" or "primarily" means 50% or greater. There are several objections to cotton, but before the present invention no satisfactory solutions to the problems or objections had been developed. The problems or objections are first that spun cellulosic materials are relatively very expensive as compared with a gauze formed of textured, continuous, multi-filament polymeric yarns such as nylon and polyester. The steps involved in forming a spun yarn are several and increase the cost thereof. Further, it is difficult to weave high cellulosic content yarns on modern, economical high speed, fluid jet looms (water or air). In the case of water jet looms the yarn tends to swell in the presence of the water and is therefore difficult to weave. Spun yarns also tend to include more defects than textured yarns, also making the processing more difficult.
Some examples of polyester or other polymeric fibers formed into a non-woven mat or web and used as a backing or base for vinyl wallcoverings are described in U.S. Pat. Nos. 4,560,643 and 4,246,311. However, the polyester or polymeric fibers in these illustrations are formed into a non-woven web or batt and impregnated with a latex binder. This is also a relatively expensive procedure leading to a different type of wallcovering. The gauze substrate envisioned by the present invention merely adapts conventional vinyl wallcoverings by affixing (embedding the substrate) into the rear surface resulting in a relatively thin wallcovering.
Previous attempts to use gauze formed of woven, continuous, multi-filament, polymeric yarns such as polyester or nylon as a wallcovering substrate have failed for two reasons. First, the textured, continuous multi-filament polymeric yarns generally tend to shrink. Secondly, polymeric materials such as polyester and nylon are generally hydrophobic and tend to repel moisture. Therefore, such yarns are not compatible to receive and maintain the resinous glue in position as the glue is curing. As a result the wallpaper does not bond to the wall surface.
Because of the tremendous savings potential to be realized from the use of woven polymeric gauze, however, efforts have continued to overcome the problems above, thereby adapting up to 100% polyester and/or nylon yarns for use in such gauze substrates. First, the advent of texturizing procedures which resulted in non-shrink polyester encouraged applicant to address seriously the hydrophobic question. After further investigation, it was found that the addition of certain selected surfactants to textured, continuous, multi-filament polyester yarn changed the hydrophobic characteristics of the yarn into more hydrophilic characteristics. The selected surfactant(s) was water dispersible, but not water soluble, so that the surfactant could work its way into the interfilamentary structure, yet not be washed out during the weaving operation. It should be noted that the hydrophobic filaments themselves were not actually made hydrophilic, rather the nature of the textured, continuous, multi-filament yarn was hydrophobic in that it no longer tended to repel moisture, but would trap the moisture within the interfilamentary structure thereof.
Not all surfactants will satisfactorily accomplish the objects of the present invention, it being determined that the surfactants selected must have the characteristics of being water dispersible, but not water soluble; having a hydrophilic, lipophilic bonding factor (HLB scale) in the range of 7-10; having a viscosity in the range of 50-100 Saybolt Universal Seconds (SUS); and having a smoke point greater than 350.degree. F. A surfactant with such characteristics will satisfactorily treat the yarn as part of the texturizing process and be compatible with the water jet weaving operation.
It is therefore an object of the present invention to provide an improved wallcovering gauze substrate.
It is another object of the present invention to provide a substrate of the type described which is formed of textured, continuous, multi-filament polyester or nylon yarn.
It is yet another object of the present invention to provide a substrate of the type described formed of yarns of the type described in which the polymeric yarns are so treated as to have a hydrophilic characteristic.
It is another object of the present invention to form a polyester or nylon gauze substrate which has hydrophilic characteristics to the extent that it will accept and hold conventional water base wallcovering glue until the glue cures thus bonding the substrate to a wall surface.
It is yet a further object of the present invention to provide a textured, continuous, multi-filament polyester or nylon yarn that has hydrophilic characteristics.